Electric horns for automobiles producing an audible warning signal commonly consist of a flexible diaphragm supported at its periphery mechanically interconnected to an electric vibratory motor and in communication with a projector for projecting the sound vibrations created by the diaphragm. The motor usually consists of an armature capable of vibrating in the direction of its axis under the influence of a "make and break" circuit, and the projector is assembled to the motor housing having an inlet substantially concentrically related to the diaphragm, and an enlarged outlet through which the sound vibrations are projected. Commonly, the motor housing subassembly is formed of metal, the housing usually being of sheet steel, and as the projector is often in the form of a spiral scroll of relatively complex configuration the projector may be of a synthetic plastic material. The diaphragm is normally mounted intermediate mounting surfaces defined upon the motor housing and projector, and a variety of fastener devices have been used to interconnect the projector to the motor housing. For instance, bolts or rivets extending through the projector and motor housing have been employed, clips or mechanical fasteners can be used to interconnect these components, it may be possible to deform a portion of the projector upon the motor housing if the projector is formed of metal, or the motor housing may include a deformable portion which can be formed over portions of the projector to produce an interconnection.
Ideally, the assembly of the projector and motor housing should be of such a nature that the interconnection is weatherproof, attractive, free of projections or extensions, concise, capable of producing a uniform assembly force throughout the periphery of the diaphragm in order to achieve consistent audio characteristics over an extended life cycle and readily achieved by high production fabrication techniques. Difficulty has been encountered in achieving these objects in the assembly of a synthetic plastic projector and metal motor housing.
It is an object of the invention to interconnect a synthetic plastic horn projector to an electric motor housing wherein the assembly supports a diaphragm throughout its periphery, and wherein the assembly will maintain consistent audio characteristics throughout the life of the horn.
Another object of the invention is to provide an assembly between a metal horn motor housing and a synthetic plastic projector wherein the assembly is free of bolts, or rivets, and produces uniform forces throughout the interconnection, and wherein the interconnecting structure is concise in configuration, and capable of producing a substantially weathertight seal.
A further object of the invention is to provide an interconnection between an electric horn motor housing and a synthetic plastic sound projector wherein a metal insert is molded into the projector and includes a continuous flange which is mechanically deformed throughout its configuration upon a flange defined upon the motor housing.
Another object of the invention is to provide a synthetic plastic horn projector utilizing a metal insert integrally molded into the projector wherein the insert includes means for facilitating the interconnection between the projector material and the insert, and the insert includes a deformable flange which may be rolled upon a horn motor housing for assembly of the projector thereto.
In the practice of the invention the electric horn includes a motor subassembly mounted within a sheet metal housing, and the housing encompasses an armature axially vibrating within an electric coil. The housing includes a substantially planar flange having a circular periphery defining a planar mounting surface to which the diaphragm and projector are secured.
The horn projector is formed of a synthetic plastic material by a molding operation, and comprises two parts which are cemented or otherwise bonded in assembled relationship.
The projector part disposed adjacent the motor housing includes a substantially flat mounting surface which is related in opposed relationship to the motor housing flange mounting surface, and the horn diaphragm is sandwiched between the mounting surfaces of the housing and projector upon suitable annular spacers. The projector includes an inlet opening centrally located with respect to the diaphragm, and a spiral or scroll air passage is defined in the projector terminating in an enlarged bell outlet.
A metal insert is molded into the projector portion disposed adjacent the diaphragm and motor housing. This insert includes a central portion having a plurality of holes defined therein for receiving the projector material during molding to insure a firm mechanical interconnection between the insert and projector. The insert also includes a peripheral region from which depends a cylindrical flange having an axis perpendicularly disposed to the plane of the insert central region. The diameter of the insert flange is slightly greater than the diameter of the motor housing flange periphery, and in assembly, the insert flange extends about the motor housing periphery, and the free end of the insert flange is rolled over upon the motor housing flange to produce a firm mechanical interconnection between the projector and motor housing.
As the insert flange is of a continuous configuration and is rolled over upon the motor housing flange throughout its configuration a uniform assembly pressure is maintained between the mounting surfaces of the motor housing and projector, which imposes a uniform assembly pressure throughout the periphery of the horn diaphragm throughout the life of the horn which will not weaken due to horn vibration, and as the insert flange closely confines the motor housing flange periphery this mechanical interconnection is concise and results in no projections or protuberances upon the horn.
As the metal insert embedded within the projector material extends throughout the width of the projector a very high strength integral assembly between the projector and insert is achieved, and as the metal of the insert flange is readily deformable over the motor housing flange consistent assembly is achievable under high production manufacturing techniques.